As a child grows, the internal harness height should be adjusted so that the straps are sitting at the right and safe height for the child.
For rear facing, the straps should always be in the slot closest the the child's shoulders or slightly above the shoulders but never below.
For forward facing, the straps should always be in the slot closest the the child's shoulders but can be either slightly above or up to 2.5cm below as a last resort.
How you adjust the restraints harness height will depend on the model and style of car restraint you have.
For our 'Twist & Lift' seats, indicated by a the 'Twist & Lift' logo at the bottom of the headrest and a red dial under the cover
Turn the red dial clockwise and raise or lower the headrest to the desired position, if the child's shoulders are just touching the bottom of the headrest move up to the next notch.
For manual adjust seats (all without the 'Twist & Lift') loosen the harness as much as possible, this will raise the spreader plate (that the ends of the harness attach to) up the back of the restraint.
Unhook the harness through the gates in the spreader plate and rethread the harness straps through the desired slot height then re-hook the harness to the spreader plate, ensuring that the harness straps are completely hooked into the spreader.